This application relates in general to compositions and methods for alleviating or preventing ischemic tissue damage.
Ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. Ischemia in brain tissue may be caused by stroke or head injury. Collateral circulation is a process in which compensatory circulation is carried out when small (normally closed) vessels open and connect two larger vessels or different parts of the same artery after an obstruction of the principal vessel supplying the blood flow has occurred. The collateral vessels then serve as alternate routes of blood supply. All people have collateral vessels, at least in microscopic form, but these vessels are normally closed. They can, however, grow and enlarge in some people with coronary heart disease or other blood vessel disease, such as in the case of stroke. Although all patients have collateral vessels, the vessel do not necessarily open and varying numbers of the vessels may open.
When an artery in the brain is blocked due to stroke or transient ischemic attack (TIA), open collateral vessels can allow blood to bypass the blockage. This collateral circulation restores blood flow to the affected part of the brain. Because not all patients naturally develop collateral circulation, it is desirable to develop methods of treatment that will increase the likelihood that collateral circulation will occur.